1. Field of the Invention
This invention relates to a charge pump circuit, and more particularly, a charge pump circuit that is capable of reducing reverse currents.
2. Description of the Prior Art
Due to requirements of low power for electronic devices, the power specification of integrated circuits (IC) is re-designed to work in a low voltage environment for reducing power consumption. For example, the IC power specification that used to be 5V before is now reduced to 3.3V or even lower than 2V. Although lower voltages are supplied to reduce power consumption, greater voltages are still needed in some situations. For example, flash memory may require a greater voltage for programming or erasing. The greater voltage is usually supplied by a charge pump circuit.
The charge pump circuits of the prior art are usually controlled by complementary clock signals. However, since the clock signals are not perfect square waves, switches of the charge pump circuits may be turned on or turned off unpredictably during transitions of voltage levels of the clock signals. In this case, unwanted reverse currents may be produced, which further increase power consumption. Therefore, how to reduce the reverse current of the charge pump circuit has become an issue to be resolved.